Air cushion vehicle

ABSTRACT

An air-cushion vehicle has a body structure including a rigid platform, and a shock absorber section of semi-rigid selfsupporting resilient material fixedly attached around the periphery of the rigid platform with the lower surface of the shock absorber section extending outwardly and downwardly below the rigid platform. A thin skirt of tough flexible material is united with the shock absorber section and extends downwardly from the peripheral region thereof. The skirt has integral mounting skirt members which are united with the outer peripheral surface and lower surface of the shock absorber section, and the shock absorber section extends beneath the rigid platform in overlapping relationship with the overlapping surfaces inclined outwardly and upwardly from the horizontal. At the front, the lower portion of the shock absorber section slopes upwardly and forwardly. The rigid platform, shock absorber section and skirt comprise a plenum chamber to which air pressure is supplied.

United States Patent [191 Ferguson 1 Jan. 9, 1973 [73] Assignee: AirCushion Vehicles, lnc., Poestenkill, N.Y.

[22] Filed: June 30, 1971 21 Appl. No.: 158,284

Related US. Application Data [63] Continuation-impart of Ser. No. 2,810,Jan. 14,

1970, Pat. No. 3,608,662.

Primary Examiner-Gerald M. Forlenza Assistant Examiner-D. W. KeenAttorneyDean S. Edmonds et al.

57 ABSTRACT An air-cushion vehicle has a body structure including arigid platform, and a shock absorber section of semirigidself-supporting resilient material fixedly attached around the peripheryof the rigid platform with the lower surface of the shock absorbersection extending outwardly and downwardly below the rigid platform. Athin skirt of tough flexible material is united with the shock absorbersection and extends downwardly from the peripheral region thereof. Theskirt has integral mounting skirt members which are united with theouter peripheral surface and lower surface of the shock absorbersection, and the shock absorber section extends beneath the rigidplatform in overlapping relationship with the overlapping surfacesinclined outwardly and upwardly from the horizontal. At the front, thelower portion of the shock absorber section slopes upwardly andforwardly. The rigid platform, shock absorber section and skirt comprisea plenum chamber to which air pressure is supplied.

14 Claims, 9 Drawing Figures PATENIEDJM 9 ma SHEET 3 [1F 4 INVENTOR HugoS. Ferguson 2 I I ATTORNEYS PATENTEUJAH 9l973 3.709 318 sum u or 4INVENTOR Hugo S. Ferguson ATTORNEY S AIR CUSHION VEHICLE RELATEDAPPLICATION This application is a continuation-in-part of applicationSer. No. 2,810 filed Jan. 14, 1970, now U.S. Pat. No. 3,608,662 by HugoS. Ferguson for Air Cushion Vehicle."

BACKGROUND OF THE INVENTION This invention relates to air-cushionvehicles and especially to relatively small vehicles capable of carryingone or two persons, although the features of the invention may beemployed on larger vehicles if desired.

The invention is particularly directed to a body platform and skirtconstruction of the. plenum chamber type which is simple, rugged, andprovides protection for both vehicle and operator under a wide varietyof conditions encountered in practice, yet is relatively inexpensive.

In application Ser. No. 2,810 a small air-cushion vehicle is describedwhich is highly maneuverable and capable of fairly high speeds overwater, ground, snow, ice, etc. For example, speeds of forty miles anhour and above have been attained. Such vehicles should be very ruggedin order to withstand shocks encountered in traveling over roughterrain, in passing from water to ground or ice and vice versa, and towithstand accidental collisions with solid objects or other vehicles.Also, shocks should be absorbed insofar aspossible to avoid seriousinjury to the rider.

The vehicle described in the aforesaid application employs anopen-bottom plenum chamber for producing the supporting air cushion, theplenum chamber being formed by the bottom of the body platform and adownwardly extending wall around the periphery of the vehicle. Theseportions of the vehicle are particularly subject to damage in passingover rough terrain, etc., and in any event the wall is subject toconsiderable wear.

The present invention utilizes certain features of the vehicle describedin the aforesaid application, with added features which improve theability of the vehicle to meet a wide variety of operating conditionswithout undue wear or damage.

SUMMARY OF THE INVENTION In accordance with the invention, theair-cushion vehicle has a body structure including a rigid platform, anda shock absorber section of semi-rigid self-supporting resilientmaterial is fixedly attached to the rigid platform around at least amajor portion of the periphery thereof, and preferably around the entireperiphery, the shock absorber section extending outwardly from the rigidplatform. A thin skirt of tough flexible material is united with theshock absorber section and extends downwardly from the peripheral regionthereof.

Advantageously the lower surface of the shock absorber section extendsoutwardly anddownwardly substantially below the rigid platform, and theshock absorber section on the sides of the vehicle extends beneath therigid platform in overlapping relationship for a substantial portion ofthe width of the section with the overlapping surfaces joined together.The overlapping relationship is desirable at the rear and front also.Further, advantageously the thin tough flexible skirt has integralmounting sheet members united respectively with the outer peripheralsurface and the lower surface of the shock absorber section.

Preferably the overlapping surfaces of the rigid platform and the shockabsorber section at the sides and rear of the vehicle are inclinedoutwardly and upwardly from the horizontal, and the same relationshipmay be employed at the front of the vehicle. Also, preferably, theflexible skirt extends downwardly and inwardly along at least the frontand sides of the vehicle, and the lower portion of the outer peripheralsurface of the shock absorber section at the front of the vehicle slopesupwardly and forwardly.

The rigid platform, shock absorber section and skirt comprise a plenumchamber, and air pressure is supplied to the plenum chamber to producean air cushion for the vehicle.

With the preferred construction the shock absorber section functionseffectively in both horizontal and ver.- tical directions. As ahorizontal shock absorber, it absorbs lateral blows from any direction,thereby protecting the vehicle and rider from collisions. As a verticalshock absorber, it absorbs shocks encountered in passing over obstacles.Small obstacles may only bend portions of the flexible skirt, and theinward tilt of the skirt at the front and sides promotes bending withoutinjury to the skirt and also reduces skirt wear. Larger obstacles maycompress or deflect the shock absorber section. At the front, due to theupward slope of the lower leading surface, much of the shock may beabsorbed by compression. However, on the sides and rear theoutwardly-extending shock absorber section can bend upwardly to absorbthe shock. The vertical shock absorber action also cushions the vehiclein making transitions from horizontal to inclined surfaces, as intraveling from a lake up an inclined bank.

The mounting sheet members integral with the skirt provide a secureunion of the skirt with the shock absorber section, capable ofwithstanding both inward and outward forces on the skirt as well asvertical forces, and also protect the periphery and lower surface of theshock absorber section against abrasion and cuts.

The downward slope of the shock absorber section increases the height ofthe inner rigid platform from the supporting surface, thereby reducingthe possibility of injury to the rigid platform. Also, the overlappingportion of the shock absorber section protects the rigid platform,especially when the shock absorber section bends in passing overobstacles. In addition, the outward and upward slope of the overlappingsurfaces assists the shock absorber section to absorb blows withoutbeing torn off.

Preferably the rigid platform is formed primarily of a foamedclosed-cell rigid plastic and.the shock absorber section is formedprimarily of a foamed closed-cell semi-rigid resilient plastic. Such astructure provides ample buoyancy, and also absorbs engine vibrationwithout requiring special shock mountings. Specific materials for therigid and semi-rigid portions of the structure, as well as for theskirt, are described hereinafter.

The vehicle has excellent stability since the shock absorber section,which forms part of the plenum chamber, cannot collapse. The downwardslope of the bottom of the shock absorber section aids stability bylimiting tilting and rolling on solid terrain. This is also true whentraveling over water, since the section is advantageously formed oflight buoyant material and, upon entering the water, creates a restoringforce which reduces the possibility of overturning.

Accordingly a combination of many desirable attributes are obtained in asimple structure which is relatively inexpensive. Other features andadvantages will in part be pointed out and in part be apparent from thefollowing description of a specific embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of anair-cushion vehicle employing features of the invention;

FIG. 2 is a longitudinal cross-section of the vehicle of FIG. 1;

FIG. 3 is a bottom view of the vehicle;

FIG. 4 is a lateral cross-section along the line 4-4 of FIG. 2;

FIGS. 5-7 are cross-sections showing details of platform, shock'absorberand skirt structure at the front, side and rear of the vehicle,respectively;

FIG. 8 is a bottom view of a modification of the front of the vehicle;and

FIG. 9 is a cross-section showing details of the modification of FIG. 8.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS Referring to FIGS. l4, a vehiclesimilar to that of application Ser. No. 2,810 is shown. A body structureincluding a rigid platform 10 has mounted thereon an air propeller lldriven by engine 12. A shroud 13 encircles the propeller to improve itsefficiency. Front steering vanes 14 are mounted for rotation aboutvertical axes to direct the downstream flow of air from the propeller tolateral angles on either side of the vehicle. Upwardly-extending rearsteering vanes 15 are mounted on each side of the vehicle. Air channelsare mounted on the body platform 10 between the front and rear steeringvanes and receive portions of the downstream flow of air under thecontrol of the front steering vanes and direct the air flow'therethrough to the rear steering vanes. The port air channel isindicated by arrow 16.

These portions of the vehicle and their operation are described indetail in the aforesaid application, to which reference is made forfurther details. Here it suffices to say that the arrangement providestwo point steering which yields a highly maneuverable vehicle capable ofexcellent performance.

Also mounted on the body platform are a seat 17 containing a gas tank, acompartment l8-for auxiliaries,

. etc. which need not be here described. Braces 19 strength the vehicleand serve as guards for the driver.

The body platform 10 has a slot-like opening 21 which supplies air underpressure from the lower portion of the propeller 11 to the plenumchamber 22 beneath the vehicle, thereby creating an air cushion whichsupports the vehicle during operation. Fixed curved vanes 23 direct aportion of the air to the forward part of the plenum chamber 22 so as toequalize the air pressure in various parts of the chamber. Mufflers 24are attached beneath the inclined floor portion 25 of the platform 10,so as to exhaust into the plenum chamber and reduce noise.

In accordance with the invention, a shock absorber section 31, 32, 33 ofsemi-rigid self-supporting resilient material is fixedly attached to therigid body platform around the periphery thereof, and extends outwardlytherefrom. A thin skirt 34, 35, 36 of tough flexible material is unitedwith the shock absorber section and extends downwardly from theperipheral region thereof. Details of the construction are shown inFIGS. 5-7.

Referring to FIG. 5, a cross-section of the structure at the front ofthe vehicle is shown. The resilient semirigid shock absorber section 31is attached to the peripheral surface 41 of the rigid body platform 10,and also to the bottom surface 42 thereof, as by contact cement or otherstrong adhesive. This portion 31 of the shock absorber section isrelatively massive since the front of the vehicle commonly is subject tomore frequent and harder blows than the sides and rear. Also thebuoyancy assists in preventing the vehicle from plowing-in whentraveling over water.

The lower surface 43 slopes downwardly and outwardly. The lower portion44 of the outer peripheral surface slopes upwardly and forwardly. Thisprovides a planing surface when the vehicle is traveling on water, andalso enables the section 31 to compress in both vertical and horizontaldirections to absorb shockswhen passing over obstacles. An angle ofabout 45 has been found satisfactory, but other angles lying generallymidway between horizontal and vertical angles may be employed ifdesired. l

The downwardly-extending skirt section 34 is inclined inwardly orrearwardly so as to enable it to bend readily in passing over obstacles,and to assist in raising the front of the vehicle when starting off inwater. Integrally formed with skirt 34 are mounting sheet members 45 and46 which are united respectively with the outer peripheral surface andthe lower surface of the shock absorber section 31, as by contact cementor other suitable means. Sections 45 and 46 not only provide a strongattachment of the skirt, but also protect the adjacent surfaces of theshock absorber section from abrasion and cutting.

Sheet member 45 could be sufficiently wide to cover the entire height ofthe inclined outer peripheral surface 44 of the shock absorber section.However, in this embodiment skirt lengths having the same cross-sectionare used for front, sides and rear of the vehicle, and sheet member 45extends only part way up surface 44. Accordingly, additional strips 47and 48 of the same material are attached in overlapping relationship soas to protect the entire surface 44 and also to protect the upper edgeof sheet member 45 frombeing snagged and torn away.

free so that they can individually flex to pass over 'obstacles.

After attaching the individual skirt lengths, strips 47,47 and 48,48 areattached thereover. Four strips are here used, two on each half of therounded bow, and shaped to enable flat sheet material to be employed.The four strips actually overlap at the center, as indicated in FIG. 3,but this is not shown in FIG. 5 since most of the bow is covered by onlytwo strips.

Referring to FIG. 6, the construction on the sides of the vehicle isshown. Here the shock absorber section 32 extends beneath the rigidplatform in overlapping relationship, and the overlapping surfaces at 51are joined together, as by contact cement. Advantageously theoverlapping surfaces at 51 are inclined outwardly and upwardly from thehorizontal, so as to provide a strong joint which resists inwardhorizontal impacts. An angle of about to the horizontal has beenemployed with success. This, together with an approximately 10 tilt ofthe lower surface of section 32, yields a total included angle of about25 at the apex of section 32. The overlap at 51 is a substantial portionof the width of the shock absorber section and protects the rigidplatform when the section bends upward in riding over an object, asindicated in dotted lines.

The tough flexible skirt 35 is united with the shock absorber section 32by the integral mounting sheet members 52 and 53, extending upwardlyalong the outer peripheral surface and inwardly along the lower surfaceof section 32, respectively. These provide both secure attachment andprotection for the shock absorber section.

Referring to FIG. 7, the construction at the rear of the vehicle isillustrated. It is similar to FIG. 6 and need not be described infurther detail. To reinforce the joint between the rigid platform 10 andshock absorber section 32, and also to protect the under surface of thelatter, a sheet 54 of the same tough material as the skirt is cementedover the joint. As shown in FIG. 3, skirts 55, 55' are cemented over thejunctions of the side and rear portions of the shock absorber sectionfor added protection. 7

The downward extent of skirt 36 at the rear is less than that of skirtsections 34 and 35 at the front and sides of the vehicle, about one inchshorter in the embodiment shown. This reduces the danger of tearing theskirt off when passing over obstacles, reduces the drag on the vehiclewhen traveling over rough water, and increases the speed somewhat due toincreased escape of air from the air cushion at the rear of the vehicle.

At the sides and rear the outer surface of the shock absorber section,covered by the attached skirt mounting sheet member, is inclinedupwardly and outwardly to provide planing surfaces which reduce anytendency of the vehicle to dig into the water when executing maneuversinvolving side or rear movement. Small angles of say 10 from thevertical are here employed.

The flexible skirt sections 35 at the sides of the vehicle may becontinuous from front to rear of the vehicle, and are advantageouslycurved or sloped inwards. This reduces wear at lower edge, since thelower portion can readily bend inwards upon contact with an obstacle.The skirt may be tapered so that the lower edge is thinner, therebyallowing the lower portion to bend more easily and reducing wear. Therear skirt section 36 is also continuous from end to end. Therear endsof the side skirt sections 35 abut the adjacent ends of the rear skirtsection 36, but are not attached thereto so as to allow each to flex asrequired without tearing at the corners. Similarly the outer ends of thefront skirt sections 34 overlap the front ends of the side skirtsections but are not attached thereto.

Referring to FIGS. 8 and 9, a modification of the front of the vehicleis shown. Here the bow section 61 as seen in FIG. 8 is an arc of acircle of large radius. The resulting increase in square footage underthe bow increases the lift from the air cushion so that a somewhatsuperior performance on rough ground is obtained. Further, the smallercurvature enables a simpler skirt construction to be employed.

Here a single length of skirt material extends across the entire bow.The peripheral mounting sheet member 45' is continuous from end to endand cemented to the inclined surface 44' of the shock absorber section31 The downwardly-extending skirt 34' and the inwardlyextending mountingsheet member 46 are slit at staggered intervals, as shown at 62 and 63in FIG. 8. This enables an initially straight length of skirt materialto be bent sufficiently to conform to the curved bow, and the slitsections of sheet member 46 are attached to the inclined surface 43 ofthe shock absorber section. The slits in skirt 34 also allow the slitsections to flex independently in passing over obstacles.

An additional protecting sheet 64 of the same material as the skirt iscemented over the entire inclined peripheral surface 44 of the bowsection, and overlaps skirt member 45, for added protection.

The shock absorber section 31 extends beneath the rigid platform 10 inoverlapping relationship and is cemented thereto. The overlappingsurfaces, indicated at 65, incline upwardly and outwardly from thehorizontal similar to the side and rear constructions of FIGS. 6 and 7so that horizontal and vertical components of a blow tend to compressthe shock absorber section 31' against the rigid platform 10, therebyenabling the blow to be absorbed without undue stress on the joint atthe overlapping surfaces. An angle of about 45 is here shown.

Various materials may be employed for different parts of the structureas desired. The following identifies materials used in the specificembodiment shown.

The rigid body platform 10 is molded of foamed, closed-cell rigidpolyurethane with a tough skin produced by maintaining the mold at asuitable temperature to form the desired skin thickness, in accordancewith considerations known in the art. A socalled 2 lbs/cu. ft. systemusing freon as the foaming agent has been employed with success,yielding a density of around 4 lbs./cu. ft. in the core and around 30lbs./cu. ft. in the skin. For added strength, fiber glass may beincorporated in the material or the exposed surfaces covered with fiberglass.

The peripheral shock absorber section 31-33 is of foamed semi-rigidpolyethylene having a substantially closed-cell structure, say percentor more closed cells. A Dow Chemical Company product sold under thebrand name ETHAFOAM 220 has been used with success. This has a densityof about 2.2 lbs./cu. ft. The material may be considered to be a solidas distinguished from liquid or gas, despite its foamed composition andresiliency, and is self-supporting and of considerable strength.

The shock absorber section is conveniently fabricated from slabs adheredby heat, cut as required,

' and then cemented to the body platform. With closedcell semi-rigidmaterial, the resistance to compression increases at a rate greater thanunity, at higher pressures, as compared to an approximately linearrelationship obtained with open-cell material, and hence is capable ofabsorbing heavy shocks without undue deformation. For example, ETHAFOAM220 compresses about 25 percent at 6 psi and about 50 percent at 15 psi.Also, the closed-cell material does not absorb water to a significantdegree.

The skirt material is ethylene vinyl acetate (EVA) having a density ofabout 0.95 and a Shore A Durometer hardness of about 90-95. Thismaterial is very tough while still being flexible, and is resistant totearing. The several skirt sections may be cut from lengths having thesame generally T-shaped cross-section, if desired. Thus in oneembodiment, on the sides as seen in FIG. 6, the width of the curvedskirt 35 was slightly under 3 inches and skirt mounting members 52 and53 were about 3% inches and 6 inches, respectively. The shirt 36 at therear was cut down about an inch. At the front (FIG. 5) the skirt sectionwas inverted so that mounting and skirt members 52, 35 on the sidebecame skirt and mounting members 34, 45. The members were aboutthree-sixteenthsinch thick near their bases and tapered to smallerdimensions at the free edges thereof.

Preferably the skirt is strong enough to withstand normal air cushionpressure without substantial deformation. This 'is approximatelyone-tenth pound per square inch in the embodiment shown, and skirtmembers as described-have been found to be sufficiently rigid tomaintain their configuration in normal traveling and yet bend readilywhen contacting an obstacle.

Although these materials are preferred at the present time, alternativematerials such as fiber glass or ABS (acrylonitrile-butadiene-styrenecopolymer) could be used for the rigid platform, and reliance placed onthe shock absorber section for buoyancy. For the skirt, possiblealternatives to EVA include black polyurethane and neoprene rubber.

As described, the skirt is separately formed and then attached to theshock absorber section to form a unitary structure. If suitablematerials become available, it may be possible to form the skirt and.mounting sheet members integrally with the shock absorber section, forexample in a manner analogous to the formation of the tough skin on therigid platform.

The vehicle specifically shown in FlGS. 1-7 is about feet long and 5%feet wide. In FIG. 6 (side) the rigid platformlfl is about-3% inchesthick inside the overlapping region and the shock absorber section 32about 4 inches thick outside the overlapping region. The shock ,absorbersection extends about 7% inches beyond the rigid platform at the top andits width at the in operation, the vehicle may move in any direction,including rearwards when turning the vehicle around to stop. The shockabsorber section absorbs lateral shocks from any direction. In passingover small obstacles such as rocks, the skirt sections may bend asrequired, without tearing or undue wear. For larger obstacles the shockabsorber section at the front can compress to absorb the shock as thevehicle passes thereover, and the shock absorber section at the sidesand rear may bend upwards to absorb the shock. The skirt mountingsheetmembers protect the shock absorber section on the periphery andbottom against abrasion and cutting, and the overlapping regions of theshock absorber section and rigid platform protect the latter. Also thedownward sloping lower surfaces of the shock absorber section maintainthe rigid platform farther off the supporting surface so that, withnormal caution on the part of the driver, the rigid platform will not bedamaged. At

the same time, the lower peripheral regions of the shock absorbersection aid vehicle stability.

The rigid platform, shock absorber section and skirt form a plenumchamber to which air pressure is-supplied, thereby producing an aircushion for the vehicle It will be noted that the area of the shockabsorber section is a substantial portion of the total supportingsurface of the plenum chamber, so that the above advantages are obtainedwhile at the same time preserving the lifting area. I,

The invention'has been described in connection with a specificembodiment showing the presently preferred construction. It will beunderstood that changes may be made therein within the spirit andscopeof the invention, and that selected features may be employed'andothers omitted as meets the judgment of the designer.

I claim:

1. An air-cushion vehicle which comprises a. a body structure includinga rigid platform,

b. a shock absorber section of semi-rigid self-sup? porting resilientmaterial fixedly attached to said rigid platform around at least a majorportion of the periphery thereof and extending outwardly therefrom withthe lower surface of the shock absorber section extending outwardly anddownwardly substantially below the rigid platform,

c. said shock absorber section on the sides of the vehicle extendingbeneath said rigidplatform in overlapping relationship'for a substantialportion of the width of the section with the'overlapping surfaces joinedtogether,

d. a thin skirt of tough flexible material united with said shockabsorber section and extending downwardly from the peripheral regionthereof,

c. said rigid platform, shock absorber section and skirt comprising aplenum chamber,

f. and means for supplying air pressure to said plenum-chamber toproduce-an air cushion for the vehicle. p

2. An air-cushion vehicle according to claim 1 in which said overlappingsurfaces of the rigid platform and shock absorber section atthe sides ofthe vehicle are inclined outwardly and upwardly from the horizontal.

3. An air-cushion vehicle according to claim 1 in which said thin skirthas mounting sheet members integral therewith which areunitedrespectively with the outer peripheral surface and the lowersurface of said shock absorber section.

4. An air-cushion vehicle which comprises a. a body structure includinga rigid platform,

b. a shock absorber section primarily of a foamed semi-rigid resilientplastic fixedly attached to said rigid platform around at least a majorportion of the periphery thereof and extending outwardly therefrom withthe lower surface of the shock absorber section extending outwardly anddownwardly substantially below the rigid platform,

. said shock absorber section on the sides and rear of the vehicleextending beneath said rigid platform in overlapping relationship for asubstantial portion of the width of the section with the overlappingsurfaces joined together,

d. a thin skirt of tough flexible material extending downwardly from theperipheral region of said shock absorber section and having mountingsheet members integral therewith which are united respectively with theouter peripheral surface and the lower surface of the shock absorbersection,

. said rigid platform, shock absorber section and skirt comprising aplenum chamber,

f. and means for supplying air pressure to said plenum chamber toproduce an air cushion for the vehicle.

5. An air-cushion vehicle according to claim 4 in which said overlappingsurfaces of the rigid platform and shock absorber section at the sidesand rear of the vehicle are inclined outwardly and upwardly from thehorizontal.

6. An air-cushion vehicle according to claim 4 in which said foamedsemi-rigid resilient plastic is of the closed-cell type.

7. An air-cushion vehicle according to claim 4 in which said skirt atthe front and sides of the vehicle extends downwardly and inwardly.

8. An air-cushion vehicle according to claim 4 in which at least thelower portion of the outer peripheral surface of said-shock absorbersection at the front of the vehicle slopes upwardly and forwardlygenerally midway between horizontal and vertical angles, and said skirtat the front of the vehicle extends downwardly and inwardly.

9. An air-cushion vehicle which comprises a. a body structure includinga rigid platform,

b. a shock absorber section of semi-rigid self-supporting resilientmaterial fixedly attached to said rigid platform around at least a majorportion of the periphery thereof and extending outwardly therefrom,

. a thin skirt of tough flexible material extending downwardly from theperipheral region of said shock absorber section and having mountingsheet members integral therewith which are united respectively with theouter peripheral surface and the lower surface of the shock absorbersection,

d. said rigid platform, shock absorber section and skirt comprising aplenum chamber,

e. and means for supplying air pressure to said plenum chamber toproduce an air cushion for the vehicle.

10. An air-cushion vehicle which comprises a. a bpdy st ructureincluding a rigid platform, b. said rigid platform being formedprimarily of a foamed closed-cell rigid plastic with a tough adherentskin,

c. a shock absorber section primarily of a foamed closed-cell semi-rigidresilient plastic fixedly attached to said rigid platform aroundsubstantially the entire periphery thereof and extending outwardlytherefrom with the lower surface of the shock absorber section slopingdownwardly and outwardly substantially below the rigid platform,

. said shock absorber section on the sides and rear of the vehicleextending beneath said rigid platform in overlapping relationship for asubstantial portion of the width of the section with the overlappingsurfaces joined together,

. at least the lower portion of the outer peripheral surface of saidshock absorber section at the front of the vehicle sloping upwardly and.forwardly generally midway between horizontal and vertical angles,

f. a thin skirt of tough flexible material extending downwardly from theperipheral region of said shock absorber section and having mountingsheet members integral therewith which are united respectively with theouter peripheral surface and the lower surface of the shock absorbersection, said skirt at the front and sides of the vehicle extendingdownwardly and inwardly,

h. said rigid platform, shock absorber section and skirt comprising aplenum chamber,

i. and means for supplying air pressure to said plenum chamber toproduce an air cushion for the vehicle.

11. An air-cushion vehicle according to claim 10 in which saidoverlapping surfaces of the rigid platform and shock absorber section atthe sides and rear of the vehicle are inclined outwardly and upwardlyfrom the horizontal.

12. An air cushion vehicle according to claim 11 in which said shockabsorber section at the front of the vehicle extends beneath said rigidplatform in overlapping relationship for a substantial portion of thewidth of the section with the overlapping surfaces inclined forwardlyand upwardly from the horizontal and joined together.

13. An air-cushion vehicle according to claim 10 in which the lower edgeof the skirt at the rear of the vehicle is substantially above theadjacent lower edges of the skirt on the sides of the vehicle.

14. An air-cushion vehicle according to claim 12 in which said rigidplastic is polyurethane, said semi-rigid plastic is polyethylene andsaid skirt is ethylene vinyl acetate.

1. An air-cushion vehicle which comprises a. a body structure includinga rigid platform, b. a shock absorber section of semi-rigidself-supporting resilient material fixedly attached to said rigidplatform around at least a major portion of the periphery thereof andextending outwardly therefrom with the lower surface of the shockabsorber section extending outwardly and downwardly substantially belowthe rigid platform, c. said shock absorber section on the sides of thevehicle extending beneath said rigid platform in overlappingrelationship for a substantial portion of the width of the section withthe overlapping surfaces joined together, d. a thin skirt of toughflexible material united with said shock absorber section and extendingdownwardly from the peripheral region thereof, e. said rigid platform,shock absorber section and skirt comprising a plenum chamber, f. andmeans for supplying air pressure to said plenum chamber to produce anair cushion for the vehicle.
 2. An air-cushion vehicle according toclaim 1 in which said overlapping surfaces of the rigid platform andshock absorber section at the sides of the vehicle are inclinedoutwardly and upwardly from the horizontal.
 3. An air-cushion vehicleaccording to claim 1 in which said thin skirt has mounting sheet membersintegral therewith which are united respectively with the outerperipheral surface and the lower surface of said shock absorber section.4. An air-cushion vehicle which comprises a. a body structure includinga rigid platform, b. a shock absorber section primarily of a foamedsemi-rigid resilient plastic fixedly attached to said rigid platformaround at least a major portion of the periphery thereof and extendingoutwardly therefrom with the lower surface of the shock absorber sectionextending outwardly and downwardly substantially below the rigidplatform, c. said shock absorber section on the sides and rear of thevehicle extending beneath said rigid platform in overlappingrelationship for a substantial portion of the width of the section withthe overlapping surfaces joined together, d. a thin skirt of toughflexible material extending downwardly from the peripheral region ofsaid shock absorber section and having mounting sheet members integraltherewith which are united respectively with the outer peripheralsurface and the lower surface of the shock absorber section, e. saidrigid platform, shock absorber section and skirt comprising a plenumchamber, f. and means for supplying air pressure to said plenum chamberto produce an air cushion for the vehicle.
 5. An air-cushion vehicleaccording to claim 4 in which said overlapping surfaces of the rigidplatform and shock absorber section at the sides and rear of the vehicleare inclined outwardly and upwardly from the horizontal.
 6. Anair-cushion vehicle according to claim 4 in which said foamed semi-rigidresilient plastic is of the closed-cell type.
 7. An air-cushion vehicleaccording to claim 4 in which said skirt at the front and sides of thevehicle extends downwardly and inwardly.
 8. An air-cushion vehicleaccording to claim 4 in which at least the lower portion of the outerperipheral surface of said shock absorber section at the front of thevehicle slopes upwardly and forwardly generally midway betweenhorizontal and vertical angles, and said skirt at the front of thevehicle extends downwardly and inwardly.
 9. An air-cushion vehicle whichcomprises a. a body structure including a rigid platform, b. a shockabsorber section of semi-rigid self-supporting resilient materialfixedly attached to said rigid platform around at least a major portionof the periphery thereof and extending outwardly therefrom, c. a thinskirt of tough flexible material extending downwardly from theperipheral region of said shock absorber section and having mountingsheet members integral therewith which are united respectively with theouter peripheral surface and the lower surface of the shock absorbersection, d. said rigid platform, shock absorber section and skirtcomprising a plenum chamber, e. and means for supplying air pressure tosaid plenum chamber to produce an air cushion for the vehicle.
 10. Anair-cushion vehicle which comprises a. a body structure including arigid platform, b. said rigid platform being formed primarily of afoamed closed-cell rigid plastic with a tough adherent skin, c. a shockabsorber section primarily of a foamed closed-cell semi-rigid resilientplastic fixedly attached to said rigid platform around substantially theentire periphery thereof and extending outwardly therefrom with thelower surface of the shock absorber section sloping downwardly andoutwardly substantially below the rigid platform, d. said shock absorbersection on the sides and rear of the vehicle extending beneath saidrigid platform in overlapping relationship for a substantial portion ofthe width of the section with the overlapping surfaces joined together,e. at least the lower portion of the outer peripheral surface of saidshock absorber section at the front of the vehicle sloping upwardly andforwardly generally midway between horizontal and vertical angles, f. athin skirt of tough flexible mAterial extending downwardly from theperipheral region of said shock absorber section and having mountingsheet members integral therewith which are united respectively with theouter peripheral surface and the lower surface of the shock absorbersection, g. said skirt at the front and sides of the vehicle extendingdownwardly and inwardly, h. said rigid platform, shock absorber sectionand skirt comprising a plenum chamber, i. and means for supplying airpressure to said plenum chamber to produce an air cushion for thevehicle.
 11. An air-cushion vehicle according to claim 10 in which saidoverlapping surfaces of the rigid platform and shock absorber section atthe sides and rear of the vehicle are inclined outwardly and upwardlyfrom the horizontal.
 12. An air-cushion vehicle according to claim 11 inwhich said shock absorber section at the front of the vehicle extendsbeneath said rigid platform in overlapping relationship for asubstantial portion of the width of the section with the overlappingsurfaces inclined forwardly and upwardly from the horizontal and joinedtogether.
 13. An air-cushion vehicle according to claim 10 in which thelower edge of the skirt at the rear of the vehicle is substantiallyabove the adjacent lower edges of the skirt on the sides of the vehicle.14. An air-cushion vehicle according to claim 12 in which said rigidplastic is polyurethane, said semi-rigid plastic is polyethylene andsaid skirt is ethylene vinyl acetate.